Field
This technology as disclosed herein relates generally to fluid flow systems and, more particularly, to air flow systems and the undesirable collection and accumulation of particulates in areas of the air flow system.
Background
Traditional fluid flow systems, in particular air flow systems, may have sections of the flow path where particulates collect and accumulate thereby restricting fluid flow. This can be due to the fact that sections along the flow path can have partial obstructions, or structures that extend laterally across the flow path with respect to the direction of the flow and that collect particulates. One specific example can be a Cabin Air Conditioning and Temperature Control System (CACTCS) having a flow path along which air flows, where a section of the flow path includes a Heat Exchanger (HX). The HX can have an array of fins, which can be the core of the heat exchanger, that extend laterally across the flow path with respect to the direction of air flow.
Particulates traveling along the flow path can collect/attach themselves on the array of fins of the HX and accumulate over time thereby restricting air flow. The reduction in air flow and the increase in pressure will necessitate a service action requiring cleaning or replacing of at least the fin section of the HX. There are known examples where aircraft CACTCS having an HX require cleaning or replacement of the HX at regular intervals that are much shorter than intended resulting in excessive maintenance cost for servicing the HX. However, the collection of particulates at certain sections along the flow path is not necessarily due to particulates attaching themselves to obstructions extending laterally across the flow path. For example, particulates can even attach themselves to the side walls around the flow path. Further, the section of the flow path where particulates collect need not be a heat exchanger. It could be any type of fluid exchanger. The fluid exchanger could be an array of baffles or vents.
In order to address the problem of particulates accumulating, a traditional electrostatic precipitator using corona wires and a positively or negatively charged surface or other filtration system could be installed upstream with respect to the section of the air flow path of concern (in the example—the FIX with fins) The corona wires of the precipitator cause a corona discharge, which is an electrical discharge brought on by the ionization of a fluid (typically air) surrounding a conductor (the corona wire) that is electrically charged. A corona wire can be a positive corona wire causing a positive ionization of the surrounding fluid, or a negative corona wire causing a negative ionization of the surrounding fluid. The polarity of the voltage applied electrically coupled from a power source will determine whether the corona wire is a negative corona or a positive corona.
Spontaneous corona discharges occur naturally in high-voltage systems unless care is taken to limit the electric field strength. The corona discharge will occur when the strength (potential gradient) of the electric field around a conductor is high enough to form a conductive region, but not high enough to cause electrical breakdown or arcing to nearby objects. Corona discharge is a process by which a current flows from an electrode (the corona wire) with a high potential into a neutral fluid, usually air, by ionizing that fluid so as to create a region of plasma around the electrode. The ions generated eventually pass charge to nearby areas of lower potential, in this case particulates traveling through, or recombine to form neutral gas molecules.
However, as the electrostatic filtration system collects particulates over time, it would also have to be cleaned or replaced. Therefore, a filtration system of this nature would not be a resolution. Further, filtration systems including cyclonic or porous membrane filtration systems will likely cause an undesirable pressure drop and may also require cleaning at shorter intervals.
A system and method is needed to reduce the service required to sections of a flow path having a tendency to collect particulates.